The present invention relates to movable bulkheads which can be positioned at predetermined locations along the length of a ship to create separate cargo holds More particularly the invention relates to movable grain bulkheads.
Typically two grain bulkheads are vertically stacked to form a temporary transverse cargo bulkhead. For the specific application of movable bulkheads to the transport of grain in cargo ships, the stacked bulkheads interlock along the line of intersection and locking pins in the ends of the bulkheads are used to locate and lock the bulkhead structure to the inner hold of the ship. Bulkheads may be loaded with a lateral pressure from a grain cargo on one side only if the adjacent hold is empty and for this reason the required strength of grain bulkheads is correspondingly high. When not in use, the bulkheads are stored at the end of the cargo hold, in a group of four. Safety laws require that doors and a fixed ladder must be provided in each bulkhead. This is for escape of dockyard workers into the next hold in the case of being trapped in a hold when filling of the hold begins or escape out of the hold in case the adjoining hold has already been filled.
Previously bulkheads have been made of a complex all steel construction consisting of a corrugated structure with plates welded to it to provide a flush surface and channels framing horizontally and vertically around the periphery. This steel structure is heavy, comprises a great number of pieces and requires many welds to hold it together.
A so-called xe2x80x9csandwich plate systemxe2x80x9d (SPS) is described in U.S. Pat. No. 5,778,813, incorporated herein by reference and British Patent Application GB-A-2,337,022, incorporated herein by reference. The sandwich plate system provides a structural sandwich plate member comprising first and second metal layers and an intermediate layer which is formed of an elastomer which is bonded to the metal layers with sufficient strength to transfer shear forces therebetween. The intermediate layer may also be a composite core as described in International Application No. WO 01/32414, incorporated herein by reference.
The object of invention is to provide a grain bulkhead which is an improvement over the prior art. A further object is to provide a grain bulkhead of a more simple construction than those of the prior art, which weighs less, comprises fewer parts and requires fewer welds to hold it together.
Further objects and advantages of the invention will become apparent from the following description.
The present invention provides a movable bulkhead for use in dividing the hold of a cargo vessel, said bulkhead comprising a sandwich plate member comprising first and second outer metal layers and an intermediate layer comprised of a plastics or polymer material bonded to said first and second outer metal layers with sufficient strength to transfer shear forces therebetween.
The movable grain bulkhead of the present invention is simple to assemble and is light whilst having the required strength and stiffness.
The movable grain bulkhead according to the present invention may further comprise an upper box beam and a lower box beam, the upper box beam forming the upper edge of the first and second sides and the lower box beam forming the lower edges of the first and second sides.
This preferred embodiment has the advantage of further reducing weight.
The movable grain bulkhead of the present invention may further comprise a plurality of forms located between the first and second layers.
This preferred embodiment also has the advantage of further reducing the weight of the movable grain bulkhead and of further structural simplification.